Configuring the BFD Protocol for RIP

The address bfd-liveness-detection command or the ip rip bfd-liveness-detection command configures the Bidirectional Forwarding Detection (BFD) protocol for RIP. The BFD protocol uses control packets and shorter detection time limits to more rapidly detect failures in a network. Also, because they are adjustable, you can modify the BFD timers for more or less aggressive failure detection.

Without BFD, when a RIP peer goes down, the routes learned from that peer are purged only after each route times out. The timeout is configurable with the timers invalid command. By default, the timeout is 180 seconds after each route was received or refreshed. Consequently routes are purged successively over varying time periods rather than all at once.

In contrast, when a BFD session exists between RIP peers, a peer that goes down is detected quickly. RIP simultaneously purges all routes learned from that peer and starts the hold-down timer for each peer.

When you issue the address bfd-liveness-detection command or the ip rip bfd-liveness-detection command on a RIP peer, the peer establishes BFD liveness detection with all BFD-enabled RIP peers. When the local peer receives an update from a remote RIP peer—if BFD is enabled and if the session is not already present—the local peer attempts to create a BFD session to the remote peer.

Each adjacent pair of peers negotiates an acceptable transmit interval for BFD packets. The negotiated value can be different on each peer. Each peer then calculates a BFD liveness detection interval. When a peer does not receive a BFD packet within the detection interval, it declares the BFD session to be down and purges all routes learned from the remote peer.

Note: Before the router can use the address bfd-liveness-detection command or the ip rip bfd-liveness-detection command, you must specify a BFD license key. To view an already configured license, use the show license bfd command.

For general information about configuring and monitoring the BFD protocol, see JunosE IP Services Configuration Guide.

address bfd-liveness-detection

ip rip bfd-liveness-detection